JP3680984B2 - Method for manufacturing battery sheet electrode - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a battery sheet electrode, and more specifically, when a battery sheet electrode is produced by applying and drying a paste material of a positive electrode or a negative electrode active material on the front and back surfaces of a current collector sheet. The present invention relates to a method for producing a battery sheet electrode in which there is no misalignment between the coated and uncoated areas of the paste material coated on the front and back surfaces of the electric sheet.
[0002]
[Prior art]
Conventionally, if this type of battery sheet electrode is a positive electrode, for example, a positive electrode active material, a conductive material (such as carbon graphite) that imparts conductivity to the positive electrode active material, and these active material and conductive material are used. A paste material mixed with a binder to be bound (organic binder, etc.) and dissolved in an organic solvent is applied to the surface of the current collector sheet such as metal foil (Al) and then dried. Yes. In the case of a negative electrode, a paste material prepared by dissolving a negative electrode active material (graphite or the like) in a solvent on the surface of a metal foil (Cu) or the like is similarly applied and dried.
[0003]
And, for example, in batteries such as electric vehicles and hybrid vehicles, a positive electrode sheet coated with a positive electrode active material on both the front and back surfaces of such a current collector sheet, and a negative electrode active material applied on both the front and back surfaces of the current collector sheet. The negative electrode sheet is wound around a separator sheet, and mounted in a battery case filled with an electrolyte solution.
[0004]
Further, in the case of a battery for an electric vehicle, the electrode sheet has a sheet width of 100 to 200 mm, and its length extends to several meters per battery. As shown to 8 (a), the uncoated area | region 62 is provided along the width direction edge of the electrode sheet S, and the tabs 64, 64, ... for current collection are provided in the uncoated area at intervals of 10 to 20 cm, for example. 8b, the positive electrode current collecting tabs 64, 64,... Are connected to the positive electrode terminal for the positive electrode sheet, and the negative electrode current collecting tab 66 for the negative electrode sheet, as shown in FIG. 66,... Are configured by connecting the group to the negative terminal.
[0005]
When manufacturing such an electrode sheet, a coating machine such as a comma roll coater or a die coater (lip coater) is generally used. It is manufactured by applying a paste material of an electrode active material to the front and back surfaces and then drying.
[0006]
[Problems to be solved by the invention]
However, in the electrode sheet manufactured in this way, the electrode active material paste material is not usually applied to both the front and back surfaces of the current collector sheet at the same time as described above. Apply and dry the electrode active material paste material on one side (for example, the front surface), then apply and dry the electrode active material paste material of the same composition on the other side (back surface) To be done.
[0007]
Therefore, as shown in FIG. 8A described above, the boundary line L between the coated region P and the uncoated region N of the electrode sheet S may not match on the front and back surfaces. Therefore, in a power battery for an electric vehicle including a hybrid vehicle, the area where the electrode active material is applied between the front and back surfaces of the electrode sheet is not required even though the electric capacity between the batteries is required to be uniform. There was a concern that the displacement of the coating region caused variations in the discharge capacity and the desired battery performance could not be obtained.
[0008]
In addition, since the paste material of the electrode active material applied to the current collector sheet surface has a property that its paste viscosity and the like are likely to change over time, the application of the paste material on the coating line It is also conceivable that the area fluctuates in the width direction, and the paste material oozes out, and the coating width changes in the width direction due to changes in the amount of leaching, etc. There was also concern that the width of the work area would be uneven.
[0009]
And so far, the active material coating area and the uncoated area of the electrode sheet are uniform in the width direction, and the electrode is intended to improve the positional deviation of the coating area on the front and back surfaces of the current collector sheet There is no way to apply an active material.
[0010]
The problem to be solved by the present invention is to produce a battery sheet electrode by applying a paste material of an electrode active material to the front and back surfaces of a current collector sheet, and to apply an active material coating region on the current collector sheet surface. And a method for producing a battery sheet electrode in which the uncoated area is not varied in the width direction over the entire length of the sheet, and the active material coating area on the front and back surfaces is less displaced over the entire length of the sheet. It is in.
[0011]
[Means for Solving the Problems]
In order to solve this problem, the present invention provides, as described in claim 1, a method for producing a battery sheet electrode by applying and drying a paste material of an electrode active material on the front and back surfaces of a current collector sheet. Detects the coated or uncoated width area of the paste material to be applied to the reference surface of the current collector sheet, and applies / uncoated paste material between the front and back surfaces of the current collector sheet When the transmission sheet is irradiated with transmitted X-rays and the transmitted X-ray intensity is relatively strong, both sides are determined to be uncoated areas, and the X-ray intensity is relative. If it is weak, it is determined that both sides are coated parts, and if it is an intermediate intensity, it is determined that the part is misaligned, thereby detecting the misaligned part, and based on these detection signals Displacement of the coating boundary line between the front and back surfaces of the current collector sheet It is an Abstract that as positive to.
[0012]
In this case, there are various methods for detecting the coated width region or the uncoated width region of the paste material on the surface serving as the reference of the current collector sheet, but the current was irradiated on the current collector sheet surface by an optical method. Utilizing the fact that the light intensity of reflected light or transmitted light of light (laser light, infrared light, etc.) is different between the coated width region and the uncoated width region is the best because non-contact measurement is possible. preferable.
[0013]
In addition, as a method of detecting the positional deviation of the boundary line of the coated / uncoated area between the front and back surfaces of the current collector sheet, the coated width area and the uncoated width area on the opposite side of the current collector sheet The boundary line is detected by a mechanical or optical method, and the positional deviation amount of the coating width is calculated by comparison with the detection result on the above-described reference surface, or the same as the above-described measurement on the reference surface A preferred example is a method in which a coating width region or an uncoated width region is detected by the above method, and both are compared by pattern matching or the like to calculate a positional deviation amount of the coating width.
[0014]
Furthermore, as a method of correcting the positional deviation of the coating boundary line between the front and back surfaces of the current collector sheet, adjust the coating width of the reference surface or the opposite surface, or the coated / uncoated region. In that case, the coating width area of the paste material is moved in the width direction of the current collector sheet without changing the coating width dimension of the paste material. The coating width dimension may be variable so that the coating area lines in the width direction of the current collector sheet can be individually adjusted.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.
First, FIG. 1 schematically shows a coating line for producing a battery sheet electrode according to the present invention.
[0016]
In this coating line 10, first, a paste material of an electrode active material is applied to one side of a current collector sheet S fed out from an unwinder (uncoiler) 12 by a front surface coating device 14. After this is dried in the drying chamber 16, the same electrode active material paste material is then applied to the opposite surface (back surface) of the current collector sheet S by the back surface coating device 18 and again dried in the drying chamber 16. After being wound, it is wound around a winding portion (recoiler) 20.
[0017]
In this case, if the manufactured sheet electrode is a positive electrode, an aluminum (Al) foil is generally used for the current collector sheet S, and if the sheet electrode is a negative electrode, a copper (Cu) foil is used for the current collector sheet S. Is generally used. In the case of manufacturing a positive electrode sheet, the paste material is composed of a positive electrode active material, a conductive material (such as carbon graphite) that imparts conductivity to the positive electrode active material, and a binder (such as an organic binder) that binds them. What was mixed and dissolved in a solvent or the like is used. In the case of a negative electrode sheet, a negative electrode active material (such as graphite) dissolved in a solvent is used.
[0018]
In this coating line 10, after the paste material is applied to the back surface of the current collector sheet S by the back surface coating device 18 (therefore, the paste material is applied to both the front and back surfaces of the current collector sheet S). There is an uncoated area on both sides of the coated area of the paste material that has already been coated and dried on the front surface of the current collector sheet S on the transport line before entering the drying chamber 16. An uncoated width measuring device 22 for measuring the width, a coated region of the paste material coated on the front and back surfaces of the current collector sheet S, and uncoated regions on both sides thereof And a coating line position deviation detecting device 24 for detecting the amount of positional deviation of the boundary line between the current and the back surface coating device 18. Coating line position that corrects misalignment of the coating line Deviation correction apparatus 26 is provided.
[0019]
The uncoated width measuring device 22, the coating line position deviation detecting device 24, and the coating line position deviation correcting device 26 are electrically connected to a central processing unit (CPU) 30, and the uncoated width measuring device. 22 and the coating line position deviation detecting device 24 are driven and controlled based on detection signals from the coating line position deviation detecting device 24.
[0020]
The uncoated width measuring device 22 has an illumination light source 42 on the front surface side of the current collector sheet S and a current collector sheet from the illumination light source 42 as shown in FIG. An optical line sensor 44 that detects reflected light of the light irradiated on the S surface is disposed.
[0021]
In this uncoated width measuring device 22, laser light or infrared rays are irradiated to the left and right ends of the sheet electrode on the reference surface (surface), and optical information obtained by white light diffraction and laser interference is formed into a line shape. Obtained by a CCD (Charge Coupled Device) sensor. The video signal obtained by the CCD sensor is digitally converted, stored in a frame memory, and subjected to data processing (image processing). The simplest method for data processing is to divide the captured screen into grid-like pixels (possible up to about 50 microns per pixel), determine the threshold value, and perform binarization processing (determining light and dark) , Measure the width. There are many methods for data processing, such as pattern matching and line segment extraction. Furthermore, as a measurement object, paying attention to the coated part, the amount of deviation from the center of the current collector and the amount of deviation from the end face of the current collector may be measured to obtain the uncoated width.
[0022]
FIG. 3 schematically shows the coating line position deviation detecting device 24. As the coating line position deviation detection device 24, three configuration modes shown in FIGS. 3A, 3B, and 3C will be described. First, FIG. 3 (a) detects the amount of positional deviation of the boundary line between the coated area and the uncoated area of the paste material coated on the front and back surfaces of the current collector sheet S by the needle stick confirmation mechanism. is there.
[0023]
3A, the needles 46 and 46 as the needle stick confirmation mechanism 45 provided on the back side of the current collector sheet S are arranged in the width direction at positions closer to both ends of the current collector sheet S in the width direction. It is provided so that it can move and can be stabbed from the back side of the current collector sheet S.
[0024]
The needles 46 and 46 are pierced from the back surface side of the current collector sheet S, and the position of the needle puncture hole (marker) is detected by the uncoated width measuring device 22 described above to detect the amount of displacement.
[0025]
For example, in FIG. 4, the range of the coated / uncoated areas on the front and back surfaces of the current collector sheet S, and the reflected light intensity detected by the optical line sensor 44 of the uncoated width measuring device 22 at that time In the state in which the boundary line between the coated area and the uncoated area on the front (front) surface of the current collector sheet S is detected as shown in the figure, the above-described positional deviation detection device When a needle puncture hole (marker) is made by the needle puncture confirmation mechanism 45 of 24, a noise signal is generated in the reflected light intensity measurement data in the region where the paste material is applied to the back surface of the current collector sheet S. The boundary between the area where the noise signal is generated and the area where the noise signal is not generated is determined as the boundary line between the coated area and the uncoated area on the back surface side of the current collector sheet S, and the front surface side The amount of deviation from the boundary line between the coated and uncoated areas is detected, Both of whether the deviation in the width direction is determined.
[0026]
It is preferable that the needle stick confirmation mechanism 45 is moved forward and backward in the vertical direction several times in a short time at high speed using air so that the needle stick hole is raised near the left and right coating boundary lines. In addition, when the coating speed is high (for example, 10 m / min or more), only the position of the position deviation detecting device 24 on the coating line is set to a low speed (1-2 m / min) using a separate dancer roll or the like. You may do it.
[0027]
The coating line position deviation detection device 24 shown in FIG. 3B detects the amount of positional deviation of the coating boundary line on the front and back surfaces of the current collector sheet S using the line sensor 48 using transmitted X-rays. It is a thing. This mechanism irradiates the current collector sheet S with X-rays from a line-shaped X-ray source 50 which is wide in the width direction of the current collector sheet and narrowed in the longitudinal direction, and transmits X-rays transmitted through the current collector sheet S. Is detected by the line sensor 48, and the uncoated width of the back surface is determined by the CPU 30 based on the detection signal. Since this method is non-destructive, the uncoated width of the back surface can be determined without scratching the current collector sheet S, so that the positional deviation of the coating can be determined efficiently.
[0028]
In addition, the calculation of the width of the uncoated part is that the X-ray intensity is strong in the case where both sides are uncoated, the X-ray intensity is weak in the case of both coated parts, and the shifted part is the intermediate intensity. Therefore, it is also possible to identify the misaligned part and calculate the uncoated width of the back surface from the coated width of the reference surface or the uncoated width.
[0029]
Further, FIG. 3 (c) is a combination of the needle stick confirmation mechanism of FIG. 3 (a) and the line sensor mechanism using transmitted X-rays of FIG. 3 (b), and rough initial setting is performed by the needle stick confirmation mechanism. If more detailed setting (control) is performed in combination with a line sensor using transmitted X-rays, the amount of coating displacement can be detected with higher accuracy.
[0030]
In place of the needle stick confirmation mechanism shown in each embodiment, the uncoated width measuring device 22 shown in FIG. 2 is provided on the back side of the current collector sheet S, and coating on the back side of the current collector sheet S is performed. The boundary line of the region / uncoated region may also be detected in the same manner as the front (front) surface side, and the amount of positional deviation of the boundary line may be obtained based on the detection data of both.
[0031]
5 and 6 show a schematic configuration of the coating line position deviation correcting device 26. FIG. This coating line position deviation correcting device 26 is a comma that rotates in a state of a predetermined gap amount between a coating roll 57 that is rotationally driven in the direction of arrow A by a motor (not shown) and the coating roll 57. A paste feeder member 52 is provided between the roll 56 and the paste material of the electrode active material on the back surface side of the current collector sheet S. At the same time, the paste feeder member 52 that regulates the width of the coating region is provided. 54 (small, lightweight, high-torque ultrasonic motor, etc.) is configured to be movable in the width direction of the current collector sheet S.
[0032]
And, for example, a coating boundary line in either the width direction of the current collector sheet S as shown in FIG. 7A by a detection signal from the uncoated width measuring device 22 and the coating line position deviation detecting device 24. If it is determined that there is a deviation (deviation amount: L), the CPU 30 issues a correction command signal to the direct motor 54 of the coating line position deviation correction device 26 so that the deviation is eliminated. The paste feeder member 52 is moved 1/2 × L in a direction to correct the deviation by the driving of. As a result, the positional deviation of the coating boundary line between the front and back surfaces of the current collector sheet S is eliminated as shown in FIG. In this embodiment, the mechanical mechanism of the paste feeder member 52 is simple and lightweight, and has a structure that can be easily operated.
[0033]
In the embodiment shown in FIGS. 5 and 6, the left and right side wall plates in the width direction of the paste feeder member 52 have an integral structure, but the coating material width of the paste material cannot be adjusted. The left and right side wall plates can be separately moved in the width direction by driving a motor so that the width of the paste material coating area can be changed. Then, the coating area widths on the front and back surfaces of the current collector sheet S are originally different, and the shift amount of the left and right coating boundary lines between the front and back surfaces is L _{1 on} the one hand and L ₂ (L ₁ ≠ L on the other hand). ₂ ) It is possible to individually adjust the left and right side wall plates of the paste feeder member 52 as shown in FIG.
[0034]
As a means for correcting (variable) the coating width, the above-described comma roll coater can change the coating width by adjusting the amount of the paste (if the paste has an appropriate viscosity, There is a proportional relationship between the amount and the coating width). A capacitance sensor that can move up and down is attached to the paste reservoir to control the paste liquid level, and the coating width may be varied (several mm).
[0035]
Furthermore, in the above-described coating line, the coating treatment of the paste material on the front (front) surface of the current collector sheet S and the coating treatment of the paste material on the back surface are performed at a separated site, Sheet electrodes are manufactured on a single line, but in small coating lines, the paste material is first coated and dried only on the front (front) surface, and then pasted on the back surface. There are also two lines of coating and drying materials. Therefore, in those equipped with these two lines, an EPC (edge position control) is attached to the unwinding position of the back surface coating line, and the uncoated width measuring device provided on the front (front) surface side coating line The coating position deviation may be corrected by moving the current collector sheet S to the left and right based on the measurement data from 22 and the detection signal from the EPC of the coating line on the back side.
[0036]
Although various embodiments have been described above, in the present invention, three control devices, that is, an uncoated width measuring device 22, a coating line position shift detecting device 24, and a coating position shift correcting device 26 are used in this way. In addition, feedback control is performed during electrode manufacturing so that the coated width and uncoated width of the front surface coincide with the coated width and uncoated width of the back surface. A stable battery that has a uniform coating width and an uncoated width over the entire length of the electrode sheet, and the coating lines on the front surface and the back surface coincide with each other because the positional deviation of the coating is corrected. Sheet electrodes can be produced.
[0037]
In this feedback control, since the positional deviation in the coating line width direction is constantly monitored, the measuring means and detecting means can also serve as product evaluation of the battery sheet, and manufacture the sheet electrode. At this stage, product quality can be guaranteed.
[0038]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the case where the present invention is applied to a comma roll type coating machine has been described. However, the present invention can also be applied to a die coater (lip coater) type coating machine. Furthermore, the present invention can also be applied to a case where a sheet electrode having a non-coated portion in the width direction is manufactured by coating a wide current collector sheet by part coating. Property can be remarkably improved.
[0039]
In addition to the above embodiment, various methods can be applied as the uncoated width measuring means or the coating line position deviation detecting means. For example, air is used as a cheaper measuring means. The flow rate type, the back pressure type, or the differential pressure type may be used. In this case, the same operation can be performed by electrically converting and controlling the air amount.
[0040]
【The invention's effect】
According to the method for manufacturing a battery sheet electrode according to the present invention, in the step of manufacturing a battery sheet electrode by applying a positive electrode or negative electrode active material paste on both surfaces of a current collector sheet constituting the positive electrode or the negative electrode and drying the paste. After the reference surface of the current collector sheet surface is coated, the left and right uncoated widths or coated widths of the reference surface are measured, and the left and right sides of the reference surface and the opposite surface of the reference surface are measured by the measurement data. By detecting the position shift of the coating line and performing feedback control on the opposite surface so as to correct the position shift of the left and right coating lines opposite to the reference surface based on the detected data The active material can be applied such that there is no positional deviation of the coating on the front and back surfaces of the sheet electrode, and the coated width and uncoated width are uniform in the width direction. Between the batteries. Oite active material weight variations caused by the positional deviation of the coating can be suppressed, can be manufactured of a large number of stable cell there is no variation of the initial capacity, it is possible to guarantee a constant product quality.
[0041]
Thus, in the present invention, the measurement means and detection means can also serve as product evaluation, and can provide a sheet electrode that guarantees a constant product quality with extremely high accuracy. It is possible to save labor and time required for the process, and the quality evaluation is non-destructive, so that the manufactured product is economically efficient without wasting it. Therefore, the present invention can be applied to the production of sheet electrodes such as batteries for electric vehicles that require uniformity of the initial discharge capacity of the battery, and is an industrially extremely useful invention.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a production coating line for battery sheet electrodes according to an embodiment of the present invention.
2 is a diagram showing a schematic configuration of an uncoated width measuring device 22 in the coating line shown in FIG. 1. FIG.
3 is a schematic configuration of the coating position deviation detecting device 24 in the coating line shown in FIG. 1, with a needle stick confirmation mechanism (a) and with a line sensor (b) using transmitted X-rays. And a combination (c) of these.
FIG. 4 is a diagram for explaining a technique for detecting a positional shift amount of a boundary line between a coated area and an uncoated area on the front and back surfaces of a current collector sheet.
5 is a perspective view schematically showing a configuration of a back surface coating device 18 and a coating line position deviation correcting device 26 in the coating line shown in FIG. 1. FIG.
6 is a view of the back surface coating device 18 and the coating line position deviation correcting device 26 shown in FIG. 5 as viewed from the front.
FIG. 7 is a diagram for explaining a method for correcting a positional shift amount of a boundary line between coated and uncoated between the front and back surfaces of a current collector sheet.
FIG. 8 is a diagram showing a configuration of a conventionally known electrode sheet (a) and a wound sheet (b) thereof.
[Explanation of symbols]
10 Sheet electrode manufacturing equipment (coating line)
14 Front coating device 18 Back coating device 22 Uncoated width measurement device 24 Coating line position deviation detection device 26 Coating position deviation correction device S Current collector sheet

Claims (1)

In a method for producing a battery sheet electrode by applying and drying a paste material of an electrode active material on the front and back surfaces of a current collector sheet,
While detecting the coating width region or the uncoated width region of the paste material applied to the reference surface of the current collector sheet,
The amount of positional deviation of the boundary line between the coated and uncoated areas of the paste material between the front and back surfaces of the current collector sheet is irradiated with transmitted X-rays, and the transmitted X-ray intensity is relatively strong. If the X-ray intensity is relatively weak, the both surfaces are determined to be the coated area, and if the intensity is intermediate between them, it is determined that the position is misaligned. By detecting the position misalignment ,
A manufacturing method of a battery sheet electrode, wherein a positional deviation of a coating boundary line between front and back surfaces of a current collector sheet is corrected based on these detection signals.

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